As a preliminary result, it appears that this pressure related temperature change in Hydrogen could account for the vast majority of the demonstrated rise in power in Celani's graph above the 10 watt baseline that the run starts at.Read the story here, along with lots of interesting comments pointing out how error-prone the methods they are using can be:
See http://www.quantumheat.org/index.php/follow/163-a-partial-explaination for the details.
That’s the big problem with cold fusion/LENR: you need to be able to consistently demonstrate a long-running reaction which generates energy well in excess of any possible chemical reaction.